Rollback (data management)
In database technologies, a rollback is an operation which returns the database to some previous state. Rollbacks are important for database integrity, because they mean that the database can be restored to a clean copy even after erroneous operations are performed.[1] They are crucial for recovering from database server crashes; by rolling back any transaction which was active at the time of the crash, the database is restored to a consistent state.
The rollback feature is usually implemented with a
Cascading rollback
A cascading rollback occurs in database systems when a transaction (T1) causes a failure and a rollback must be performed. Other transactions dependent on T1's actions must also be rollbacked due to T1's failure, thus causing a cascading effect. That is, one transaction's failure causes many to fail.
Practical database recovery techniques guarantee cascadeless rollback, therefore a cascading rollback is not a desirable result. Cascading rollback is scheduled by dba.
SQL
SQL refers to Structured Query Language, a kind of language used to access, update and manipulate database. In
A ROLLBACK
statement will also release any existing savepoints that may be in use.
In most SQL dialects, ROLLBACK
s are connection specific. This means that if two connections are made to the same database, a ROLLBACK
made in one connection will not affect any other connections. This is vital for proper
See also
Notes
- ^ "Database Rollback – What and Why". 3 November 2019. Retrieved 16 April 2022.
- ^ Ben Richardson (26 December 2019). "Rollback SQL: Rolling back transactions via the ROLLBACK SQL query". Retrieved 16 April 2022.
References
- ISBN 978-0-321-36957-4.
- "ROLLBACK Transaction", Microsoft SQL Server.
- "Sql Commands", MySQL.